For amides such as, for example, nicotinamide, a vitamin of the vitamin B complex which is essential to animals and man, a number of biotechnological processes are already known. Generally, it is known that microorganisms containing nitrile hydratase convert nitriles to the corresponding amides. Thus EP-A-0 188 316 describes a process for the preparation of nicotinamide starting from 3-cyanopyridine using microorganisms of the genus Rhodococcus, Arthrobacter or Microbacterium. 
A disadvantage of this process is that these micro-organisms have only a low activity for the conversion of 3-cyanopyridine to nicotinamide.
EP-A-0 307 926 describes the conversion of 3-cyano-pyridine to nicotinamide by means of microorganisms of the species Rhodococcus rhodochrous J1. In order that these microorganisms catalyse the desired conversion, they must be induced.
A further disadvantage of this process is that Rhodococcus rhodochrous J1 is red-coloured and accordingly a discoloration of the product takes place. In addition, this microorganism has a low heat stability and is inhibited, for example, by the substrate 3-cyano-pyridine.
A further process for the preparation of nicotinamide starting from 3-cyanopyridine by means of microorganisms of the species Rhodococcus rhodochrous J1 is described in EP-A-0 362 829. In order to increase the specific activity of the microorganisms containing nitrile hydratase, urea or a urea derivative was added to the culturing medium as an inducer. As in the process described beforehand, a discoloration of the product also takes place in this process.
In addition, WO 95/17 505 describes a process for the preparation of aromatic amides starting from the corresponding nitriles by means of microorganisms of the species Rhodococcus rhodochrous M33. A disadvantage of this process is the red colouration of Rhodococcus rhodochrous M33 and also the high KM value for the substrate 3-cyanopyridine.